Search PubMed⌕ Search

Biomedical subjects

A J Smout

Publications and source records attributed to A J Smout.

At least 55 records · Page 3Linked to original sources
PubMed1999

Characterization of small intestinal pressure waves in ambulant subjects recorded with a novel portable manometric system.

The organization of lumen-occlusive pressure waves is believed to be an important determinant of luminal flow. At present, little is known about the organization of small intestinal pressure waves in humans. The aim of the present study was to characterize the spatiotemporal organization of small intestinal pressure waves using a portable 12-channel micromanometric system. Small intestinal pressures were recorded from six duodenal (1 cm apart) and six jejunal (1 cm apart) sites after a standard lunch (1892 kJ) and dinner (3305 kJ) and an overnight fast in seven ambulant subjects. Postprandially, the number of isolated pressure waves and the number of pressure wave sequences that spanned 1 and 2 cm decreased over time (P = 0.04, P = 0.003, and P = 0.0001) and were higher after lunch than dinner (P = 0.04, P = 0.02 and P = 0.04), in contrast to the number of long-spanned pressure wave sequences, which remained constant over time and were not influenced by the meal. The number of isolated pressure waves and pressure wave sequences over 1-5 cm recorded in the early postprandial period were higher than during the 30-min period of nocturnal phase II (P < 0.01). In conclusion, prolonged recording of small intestinal motility in ambulant subjects using a perfused manometric system is feasible. Postprandial recordings showed that the spatiotemporal organization of pressure waves is time- and meal-dependent.

Adult↗
PubMed1999

The effect of cisapride on duodenal acid exposure in the proximal duodenum in healthy subjects.

AIM: To investigate the effect of the prokinetic drug, cisapride, on fasting and postprandial acid exposure in the proximal duodenum. METHODS: Using a double-blind, placebo-controlled crossover study design, 12 healthy male volunteers were studied. After 1 week of dosing (cisapride 20 mg b.d. orally or placebo), fasting and postprandial antroduodenal pH-and pressure-recordings were made. Using a small-caliber (4 mm) catheter, containing one antral and two duodenal pH electrodes, and two antral and three duodenal pressure recording sites. Transmucosal potential difference was measured to ensure proper catheter position. Infusions of 0.1 N HCl were given in the duodenal bulb. RESULTS: Endogenous acidification of the duodenal bulb occurred more frequently during phase II and postprandially, compared to phase I (P<0.001). During phase I, alkalinization of the antrum was observed. Cisapride significantly increased the postprandial number of duodenal acidic periods (P<0.02), but shortened their duration (P<0.04). The duodenal motor response elicited by exogenous acid was lower during phase I (P<0.05). CONCLUSIONS: Antral and proximal duodenal acidity vary with the phases of the interdigestive motor complex. Cisapride shortens the individual periods of duodenal acidification.

Adult↗
PubMed1999

The effect of Helicobacter pylori eradication on intragastric pH during dosing with lansoprazole or ranitidine.

BACKGROUND: The antisecretory effect of omeprazole on intragastric pH is decreased in the absence of Helicobacter pylori. AIM: To investigate the effect of H. pylori eradication on intragastric pH during lansoprazole or ranitidine dosing in 41 asymptomatic H. pylori-positive subjects. METHOD: Two groups of healthy H. pylori-positive volunteers were investigated. One group was dosed with lansoprazole 30 mg at 08.00 hours for at least 8 days, before and after 2 weeks of placebo-controlled double-blind eradication therapy using ranitidine bismuth citrate 400 mg b.d. and clarithromycin 500 mg b.d. The other group was dosed with ranitidine 300 mg at 23.00 hours for at least 8 days using the same trial design. An upper endoscopy was performed to establish H. pylori status by rapid urease test, culture and histology before both periods of dosing. Twenty-four hour intragastric pH recording was performed on the final day of all periods of dosing. RESULTS: H. pylori eradication significantly decreased the intragastric pH reached during lansoprazole treatment throughout all periods of the day. Intragastric pH during ranitidine treatment was not affected by H. pylori eradication, except for the late-night period. CONCLUSION: H. pylori eradication has a more pronounced effect on the acid-inhibiting properties of lansoprazole than on those of ranitidine.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1999

The effect of hyperglycaemia on cerebral potentials evoked by rapid rectal distension in healthy humans.

BACKGROUND: Acute hyperglycaemia affects the perception of sensations arising from the gastrointestinal tract. The mechanisms responsible for this effect are unknown. Recordings of cerebral evoked potentials (EPs) can be used to assess the integrity of visceral afferent pathways. Our aim was to determine whether hyperglycaemia affects EPs elicited by rectal distension in healthy humans. MATERIALS AND METHODS: Twelve healthy men, aged 19-31 years, were studied. A manometric catheter, incorporating a rectal balloon, was positioned 7-10 cm from the anal verge. Balloon distensions at both 'low' ( approximately 20 mL) and 'high' ( approximately 28 mL) volumes were performed, in a single-blind, randomized order, during both euglycaemia (4 mmol L-1) and hyperglycaemia (12 mmol L-1). EPs were recorded from a midline scalp electrode (Cz, International 10-20 system) and averaged for each series of 50 distensions. EP latencies and interpeak amplitudes were calculated. RESULTS: Polyphasic EPs were recorded in all but one subject. Although the blood glucose concentration had no significant effect on the latencies of the EP peaks elicited by either 'low'- or 'high'-volume balloon distension, the interpeak amplitude (P1-N1) was greater during hyperglycaemia than during euglycaemia at the 'low' balloon volume (6.3 +/- 1.2 microV vs. 4.8 +/- 1.0 microV, P < 0.05). The blood glucose concentration had no significant effect on the perception of rectal balloon distension. CONCLUSIONS: We conclude that in normal subjects acute hyperglycaemia increases the amplitude of the cerebral EP elicited by rectal balloon distension at low balloon volumes, suggesting that the effects of hyperglycaemia on gastrointestinal sensation may be mediated by central mechanisms.

Adult↗
PubMed1999

Pitfalls in the analysis of electrogastrographic recordings.

Electrogastrography (EGG) is a noninvasive method to study gastric myoelectrical activity in humans. Because frequency characteristics are the most reliable parameters and visual analysis of the EGG recordings is notoriously difficult, automated frequency analysis, especially running spectrum analysis, is often used. However, EGG frequency spectra can be misinterpreted easily. Movement artifacts and noise from various sources can result in abnormal frequency spectra with significant power in the low-frequency and high-frequency range, or even make the EGG completely uninterpretable. Signals that differ from a sinusoid waveform have harmonics in the high-frequency range of the spectrum and may be interpreted as abnormal. Visual inspection of raw signals and frequency spectra remains essential in the analysis of EGG signals. The value of computerized analysis should not be overrated. EGG is an important research tool, but a clinical role still needs to be established.

Animals↗
PubMed1999

Coffee and gastrointestinal function: facts and fiction. A review.

BACKGROUND: Effects of coffee on the gastrointestinal system have been suggested by patients and the lay press, while doctors tend to discourage its consumption in some diseases. METHODS: The literature on the effects of coffee and caffeine on the gastrointestinal system is reviewed with emphasis on gastrointestinal function. RESULTS: Although often mentioned as a cause of dyspeptic symptoms, no association between coffee and dyspepsia is found. Heartburn is the most frequently reported symptom after coffee drinking. It is demonstrated that coffee promotes gastro-oesophageal reflux. Coffee stimulates gastrin release and gastric acid secretion, but studies on the effect on lower oesophageal sphincter pressure yield conflicting results. Coffee also prolongs the adaptive relaxation of the proximal stomach, suggesting that it might slow gastric emptying. However, other studies indicate that coffee does not affect gastric emptying or small bowel transit. Coffee induces cholecystokinin release and gallbladder contraction, which may explain why patients with symptomatic gallstones often avoid drinking coffee. Coffee increases rectosigmoid motor activity within 4 min after ingestion in some people. Its effects on the colon are found to be comparable to those of a 1000 kCal meal. Since coffee contains no calories, and its effects on the gastrointestinal tract cannot be ascribed to its volume load, acidity or osmolality, it must have pharmacological effects. Caffeine cannot solely account for these gastrointestinal effects. CONCLUSIONS: Coffee promotes gastro-oesophageal reflux, but is not associated with dyspepsia. Coffee stimulates gallbladder contraction and colonic motor activity.

Caffeine↗
PubMed1999

Validation and value of an enzyme-linked immunosorbent assay for Helicobacter pylori in primary care.

BACKGROUND: Helicobacter pylori infection is related to gastric ulcer and carcinoma. In this study we validated the Pyloriset EIA-G New (a quantitative enzyme-linked immunosorbent assay) in a general practice population. The implications of eradication in case of a positive result were assessed. METHODS: One hundred and fifteen subsequent patients, enrolled in a randomized clinical trial evaluating the optimal strategy for treatment of dyspeptic patients in primary care, were included. Using biopsy as gold standard, we calculated the sensitivity and specificity of the test. RESULTS: The sensitivity and specificity of the test were 91% (95% confidence interval (CI) = 86% to 97%) and 78% (95% CI = 75% to 82%), respectively. Eradication of H. pylori would be indicated in 8 of 57 positive patients, since these actually had a peptic ulcer. In the other 49 patients eradication therapy would be unnecessary. CONCLUSION: The Pyloriset EIA-G New is a reliable test in primary care. However, a serologic test-and-treat strategy in all dyspeptic patients cannot be recommended.

Adult↗
PubMed1999

Clinical relevance of antroduodenal manometry.

OBJECTIVE: To evaluate the outcome of antroduodenal manometry studies and their effect on the clinical treatment of patients. DESIGN: A retrospective review of clinical antroduodenal manometric studies performed between September 1990 and March 1997 (n = 109). SETTING: Tertiary referral centre. MAIN OUTCOME MEASURES: The predominant symptom, the indication for the study, the outcome and the clinical impact were scored. A positive impact was defined as an outcome that resulted in an alteration of the management of the patient (medication, surgery, feeding), established a new diagnosis, or resulted in new investigations or in referral to another specialist. RESULTS: Full records were obtained from 91 studies in 85 patients (mean age 43 years). Nausea and vomiting were the most predominant symptoms (37.4%). In 49.5% of the cases, the test was performed due to suspicion of a generalized motor disorder. A normal outcome was found in 37 studies. Non-specific motor abnormalities were reported in 72% of the studies with an abnormal outcome. Pseudo-obstruction was diagnosed in 20%. The manometric studies resulted in a new therapy in 12.6%, a new diagnosis in 14.9%, and referral to another specialist in 8%. A positive clinical impact was found in 28.7% of the patients. CONCLUSION: Antroduodenal manometry can be a helpful diagnostic technique in a specialized centre. More research is needed to gain insight into the significance of the large number of non-specific abnormalities that are often found.

Adolescent↗
PubMed1999

Columnar lined oesophagus and intestinal metaplasia: current concepts.

Barrett's oesophagus is a condition where the distal oesophagus is lined with columnar epithelium. For the diagnosis intestinal metaplasia has to be found and a minimal length of 3 cm is required for the columnar-lined segment. It is well known that patients with the traditional Barrett's oesophagus have a higher risk of developing adenocarcinomas in the metaplastic segment. The clinical significance of shorter metaplastic segments and intestinal metaplasia at the gastro-oesophageal junction is much less certain. Different definitions are in use and the increasing number of studies dealing with these mucosal changes therefore may create confusion. In this article, the current knowledge concerning epidemiology, pathophysiology, clinical associations, diagnostic possibilities including endoscopy, pathology, measurement of differences in electrical potential, and treatment of columnar-lined oesophagus of any length and of intestinal metaplasia at the gastro-oesophageal junction is reviewed. Furthermore, the need for a consistent definition is emphasized.

Adenocarcinoma↗
PubMed1999

Effect of coffee on gastro-oesophageal reflux in patients with reflux disease and healthy controls.

BACKGROUND: Many patients with gastro-oesophageal reflux disease (GORD) report that coffee aggravates their symptoms and doctors tend to discourage its use in GORD. OBJECTIVE: To assess the effect of coffee ingestion on gastro-oesophageal acid reflux. DESIGN: A randomized, controlled, crossover study. PARTICIPANTS: Seven GORD patients and eight healthy subjects. METHODS: After 1 day of coffee abstinence, participants underwent 24-h oesophageal pH and manometric monitoring. At well-defined times, they ingested either 280 ml of regular paper-filtered coffee or 280 ml of warm water. Coffee or water was drunk 1 h after breakfast, during lunch, 1 h after dinner and after an overnight fast Reflux and oesophageal motility parameters were assessed for the first hour after each coffee or water intake. RESULTS: Coffee had no effect on postprandial acid reflux time or number of reflux episodes, either in GORD patients or in healthy subjects. Coffee increased the percentage acid reflux time only when ingested in the fasting period in the GORD patients (median 2.6, range 0-19.3 versus median 0, range 0-8.3; P = 0.028), but not in the healthy subjects. No effect of coffee on postprandial lower oesophageal sphincter pressure (LOSP), patterns of LOSP associated with reflux episodes or oesophageal contractions was found. CONCLUSION: Coffee has no important effect on gastro-oesophageal acid reflux in GORD patients, and no effect at all in healthy subjects.

Adult↗
PubMed1999

24-h recording of intragastric pH: technical aspects and clinical relevance.

BACKGROUND: Information about gastric acid secretion and gastric acidity can be obtained using several techniques but, presently, continuous intragastric pH recording is probably the one applied most frequently. This paper aims to review the technical aspects and some important applications of intragastric pH monitoring in research and clinical practice. METHODS: Literature review. RESULTS: Most studies on intragastric pH are performed with either glass or antimony electrodes. Optimal measurement of 24-h intragastric pH requires accurate calibration of the pH measuring system, exact positioning of the pH electrodes, and a sufficient sample rate. Depending on the aim of the study the results of intragastric pH monitoring are expressed either as median H+ activity or as median pH values. Gastric acidity shows a circadian rhythm, modified by buffering meals and nocturnal duodenogastric reflux. In health, age, gender and smoking habits are known to influence gastric acidity. In duodenal ulcer disease an increased gastric acidity is found and in patients with gastric ulcer gastric acidity is decreased. In GERD, no relation between reflux oesophagitis and gastric acidity is found. Helicobacter pylori affects intragastric pH most pronounced during acid inhibitory therapy, both in DU patients and in healthy subjects. In the absence of H. pylori the effect of proton-pump inhibitors on intragastric pH is much less than in the presence of the microorganism, whereas the effect of ranitidine on intragastric pH is barely affected by the H. pylori status. CONCLUSIONS: Despite some limitations, intragastric pH monitoring provides important information about gastric acidity.

Circadian Rhythm↗
PubMed1999

Primary oesophageal motility disorders: how primary are they?

The normal regulation of oesophageal peristalsis is complex. Nitric oxide-containing inhibitory neurons and cholinergic excitatory nerve fibres play the key roles. In the so-called primary oesophageal motility disorders, the coordination of oesophageal contractions and lower oesophageal sphincter function is disturbed (achalasia, diffuse oesophageal spasm), or the amplitudes of peristaltic contractions are abnormally high (nutcracker oesophagus). This article focuses on the pathophysiology of achalasia and nutcracker oesophagus. There is evidence that achalasia and nutcracker oesophagus should not be considered parts of one and the same range of diseases.

Esophageal Achalasia↗
PubMed1998

Disturbed solid-phase gastric emptying in functional dyspepsia: a meta-analysis.

Functional dyspepsia is a common disorder with a diverse pathophysiological background, but the role of motility disorders in functional dyspepsia remains unclear. We aimed to quantify the relationship between disturbed gastric emptying and functional dyspepsia, using a meta-analytic approach. Through a structured literature search of Medline and Embase from 1983 to 1996, we selected all studies in which scintigraphic solid-phase gastric emptying was measured in both functional dyspeptic patients and controls. Seventeen studies involving 868 dyspeptic patients and 397 controls were pooled. Gastric emptying in patients with functional dyspepsia was 1.46 (1.23-1.69) times slower than controls; the proportion of patients with abnormally slow emptying was either 37% (34-40%, simple numeric pooling) or 39% (29-49%, weighted pooling). We conclude that gastric emptying of solids in patients with functional dyspepsia is 1.5 times slower than in healthy controls and that a significant delay of emptying is present in almost 40% of patients with functional dyspepsia.

Dyspepsia↗
PubMed1998

Proximal gastric motor activity in response to a liquid meal in type I diabetes mellitus with autonomic neuropathy.

Disordered gastric emptying occurs in 30-50% of patients with diabetes mellitus. Although the rate of gastric emptying is dependent on the integration of motor activity in different regions of the stomach, there is limited information about the function of the proximal stomach in diabetes mellitus. In the present study the response of the proximal stomach to a liquid meal was examined in eight diabetic patients with autonomic neuropathy and gastrointestinal symptoms and in 10 healthy volunteers, using an intragastric bag connected to an electronic barostat. Postprandial relaxation of the proximal stomach was measured as an increase of intragastric bag volume at a constant pressure level of 1 mm Hg above the intraabdominal pressure. During the experiment the blood glucose levels were maintained within the euglycemic range. Before ingestion of the meal the intragastric bag volume was larger in the diabetic patients than in the healthy volunteers, 234.4 +/- 29.1 ml vs 155.3 +/- 15.3 ml (P = 0.06). The maximum volume was not different in diabetics compared to the healthy controls (386.3 +/- 45.2 ml versus 399.0 +/- 35.2 ml). However, the maximum volume increase was significantly less in diabetics (143.7 +/- 38.6 ml) compared to the controls (231.4 +/- 30.5 ml, P < 0.04). Bloating was inversely correlated with the volume changes, which suggests that impaired relaxation of the proximal stomach may play a role in the genesis of this sensation. In conclusion, this study shows a lower fasting fundal tone and a decrease in volume change of the gastric fundus after a nutrient drink in patients with autonomic neuropathy due to type I diabetes mellitus. These abnormalities may play a role in the abnormal distribution of food, disordered liquid gastric emptying, and in the genesis of the sensation of bloating observed in these patients.

Autonomic Nervous System Diseases↗
PubMed1998

Function of the proximal stomach after Nissen fundoplication.

BACKGROUND: After Nissen fundoplication patients frequently report upper abdominal (dyspeptic) symptoms. Theoretically, these symptoms may be the result of changes in function of the proximal stomach as induced by fundoplication. METHODS: In this case-control study the response of the proximal stomach to both distension by an air-filled bag and a liquid meal were evaluated with the use of a barostat. In 12 patients after fundoplication and 12 healthy volunteers (age- and sex-matched) perception of symptoms was evaluated during both bag distension and liquid meal stimulus. RESULTS: The minimal distending pressure required to overcome the intra-abdominal pressure was significantly different between patients and controls (mean(s.e.m.) 9.34(0.26) versus 6.73(0.43) mmHg; P < 0.001). There was no difference between groups in either the fasted state, volume-pressure curve (compliance) or total symptom score. After ingestion of the liquid meal the adaptive relaxation in the fundoplication group was significantly less than that in controls (mean(s.e.m.) 150(29.2) versus 244(34.8) ml; P = 0.04). CONCLUSION: This study showed that after Nissen fundoplication compliance of the proximal stomach is no different from that in healthy volunteers. Postprandial relaxation of the proximal stomach is decreased and this abnormality may be involved in the pathogenesis of reported dyspeptic symptoms.

Adult↗
PubMed1998

Effect of meal temperature on the frequency of gastric myoelectrical activity.

It was hypothesized that the transient post-prandial decrease of the dominant frequency in the electrogastrogram (EGG) is related to the temperature of the meal. In a randomized three-period cross-over design. EGG recordings were made in 10 healthy volunteers. A liquid meal (36 kcal, 300 mL) was ingested at either 4, 37 or 55 degrees C. The changes in the dominant EGG frequency that occurred in the first 25 min postprandial were calculated using running spectrum analysis. After the meal a transient shift in frequency was seen, which was significantly greater after the cold meal than after the other meals (P < 0.001), with a greater decrease in the dominant frequency (4 degrees C: -0.75 [-0.92(-)-0.68], 37 degrees C: -0.34 [-0.51(-)-0.18], 55 degrees C: -0.30 [-0.45(-)-0.12] cpm; P = 0.020) and a longer duration (4 degrees C: 16 [13-19], 37 degrees C: 12 [6-14], 55 degrees C: 5 [3-8] min; P = 0.014). No differences were found between the 37 degrees C and 55 degrees C meals, the power ratios or the number of dysrhythmias. The magnitude of the postprandial shift in frequency of gastric myoelectrical activity depends on the temperature of the meal. Meal temperature should be taken into account in studies on postprandial gastric motility.

Adult↗
PubMed1998

A novel portable perfused manometric system for recording of small intestinal motility.

The development of solid-state catheters with miniature pressure transducers and portable dataloggers with a large memory capacity has allowed recording of gastrointestinal motility in ambulant subjects. Developments in silicone rubber extrusion technology made it possible to build a perfused manometric system, using a perfused manometric assembly requiring a low volume of perfusate. In the present study the feasibility of recording and automated analysis of small intestinal motility using a perfused multiple lumen manometric system was evaluated in seven healthy volunteers. Pressures were recorded from 12 sideholes arranged in four clusters spaced at 10-cm intervals from the catheter tip. Each channel was perfused at 0.15 mL min-1 with degassed water by a portable, low-compliance, perfusion pump. The 12 sidehole recording channels were connected to external transducers mounted on a belt. Pressure data were stored in two dataloggers. Motility was recorded in the sitting (30 min), and supine (30 min) position, during walking (30 min) and postprandially (90 min). Using purpose-built software baseline variations were corrected for and manometric variables (number of pressure waves, mean amplitude and motility index) calculated. Bench testing of the manometric assembly showed a median baseline pressure offset of 4.2 kPa (range 3.7-10.1) and upon occlusion a rise rate of 27.8 kPa sec-1 (range 19.7-30.8). Changes in body position affected baseline pressures so that compared to the supine position changes in baseline pressure varied between 1.5 +/- 0.7 kPa and 1.9 +/- 0.6 kPa during sitting (P < 0.02), and between 1.7 +/- 0.7 kPa and 1.5 +/- 0.9 kPa during walking (P < 0.03). Manometric recordings obtained during the fasting period showed an increase in small intestinal motor activity during walking. In the postprandial period no differences in motility variables were observed within one cluster and in time. Recording of small intestinal motility with a multiple-channel silicone rubber manometric assembly with a portable perfusion system is a feasible technique which is relatively inexpensive. Computer-assisted data processing allows for adequate elimination of artefacts and automated numerical analysis.

Adult↗